We propose to use poliovirus as a paradigm for utilizing three-dimensional structural data to design antiviral drugs. Our long range goals will be threefold: 1) to develop a data base of structures of drug-target complexes, 2) to develop protocols for using these structures for drug design, and 3) to design novel drugs with improved activity or a broadened spectrum of activity. These drugs would be of considerable medical and economic significance for prophylaxis of rhinovirus induced common cold (which account for up to 80% of the colds in the United States) and for early intervention in poliomyelitis and coxsackievirus induced diseases. In addition, because of similarities in the proposed targets across a wide range of RNA viruses, the drugs identified in these studies could serve as useful lead compounds for the development of antivirals for treatment of a wide variety of other significant human and veterinary diseases. Initial studies will focus on crystallographic studies of complexes between poliovirus and a series of well-characterized compounds (several of which are entering trials as antirhinovirus agents) which bind virions and block productive cell attachment or cell entry. The crystallographic studies will include complexes of antiviral agents made by Janssen Pharmaceutica and by Sterling-Winthrop with the Sabin strain of type 3 and the Mahoney strain of type 1 poliovirus. The crystallographic studies will also include the structures of drug resistant variants (which will be selected and sequenced by Roland Rueckert at the University of Wisconsin). The structures of the complexes will be compared with the structures of complexes of similar agents with rhinovirus 14 and rhinovirus 1a (currently being studied by Rossmann et. al at Purdue University). The information gained from the structures will be used to design and synthesize compounds with altered activities and specificities (in collaboration with Janssen Pharmaceutica and with K.C. Nicolau at RISC). As these studies progress we will expand the program to include additional targets for drug design, beginning with the poliovirus RNA-dependent RNA- polymerase (3Dpol) and the protease responsible for the cleavage of capsid protein precursors (3CD). Sources of large amounts of highly purified protein have been identified for both 3D and 3CD. Samples of 3D are in the early phase of crystallization screens, and samples of 3CD are expected prior to the beginning of the proposed funding period. We propose to produce crystals of these enzymes, to solve the structure of the free enzymes, and enzyme-inhibitor complexes, and to utilize this structural information, together with the experience gained from the design of uncoating inhibitors, to design compounds with antiviral activity.